It is easily possible to change with Pod "Character Designer" a property of a character format. For example, in a template file of a FM book, when a character style is selected, the change of one property, e.g. color, could be updated with "Update Style" button when the cursor position is not in a particular paragraph of a body page. Next action will be to either retain or remove overrides.
var charfmt = doc.GetNamedCharFmt(varcol);
// var chrfmt = doc.GetNamedObject(Constants.FO_ChrFmt, varcol);
if (charfmt.ObjectValid() == true)
charfmt.Color = "Black";